Bovine Erythrocyte Superoxide Dismutase Research Articles

A Transverse Tubule NADPH Oxidase Activity Stimulates Calcium Release from Isolated Triads via Ryanodine Receptor Type 1 S -Glutathionylation

We report here the presence of an NADPH oxidase (NOX) activity both in intact and in isolated transverse tubules and in triads isolated from mammalian skeletal muscle, as established by immunochemical, enzymatic, and pharmacological criteria. Immunohistochemical determinations with NOX antibodies showed that the gp91(phox) membrane subunit and the cytoplasmic regulatory p47(phox) subunit co-localized in transverse tubules of adult mice fibers with the alpha1s subunit of dihydropyridine receptors. Western blot analysis revealed that isolated triads contained the integral membrane subunits gp91(phox) and p22(phox), which were markedly enriched in isolated transverse tubules but absent from junctional sarcoplasmic reticulum vesicles. Isolated triads and transverse tubules, but not junctional sarcoplasmic reticulum, also contained varying amounts of the cytoplasmic NOX regulatory subunits p47(phox) and p67(phox). NADPH or NADH elicited superoxide anion and hydrogen peroxide generation by isolated triads; both activities were inhibited by NOX inhibitors but not by rotenone. NADH diminished the total thiol content of triads by one-third; catalase or apocynin, a NOX inhibitor, prevented this effect. NADPH enhanced the activity of ryanodine receptor type 1 (RyR1) in triads, measured through [3H]ryanodine binding and calcium release kinetics, and increased significantly RyR1 S-glutathionylation over basal levels. Preincubation with reducing agents or NOX inhibitors abolished the enhancement of RyR1 activity produced by NADPH and prevented NADPH-induced RyR1 S-glutathionylation. We propose that reactive oxygen species generated by the transverse tubule NOX activate via redox modification the neighboring RyR1 Ca2+ release channels. Possible implications of this putative mechanism for skeletal muscle function are discussed.

Temperature dependence of superoxide dismutase activity in plankton

The effect of temperature (from 1 to 37 °C) on in vitro effective superoxide dismutase (SOD) activity of several organisms was investigated and compared. Antarctic plankton, cultures of the alga Nannochloropsis sp., and the cyanobacterium Synechococcus strain WH 7803, and pure bovine erythrocyte SOD was studied. It was found that in all cases SOD activity increased with decreasing temperature within the temperature range assayed, in the Polar as well as the temperate plankton cells. This behavior of SOD is counterintuitive in terms of our experience when looking at enzyme activity or any other chemical reaction. We suggest a theoretical explanation for this apparently odd behavior. The advantage of such behavior is that the same amount of antioxidant will act better under low temperatures when reactive oxygen species (ROS) increase. Moreover, this protective process would act in vivo at a faster pace than the ex novo enzyme synthesis.

Metal ion chelating peptides with superoxide dismutase activity

The superoxide dismutase activities of two novel synthetic chelating peptides are reported. The peptides comprise a polyaminocarboxylic acid chelator (EDTA) conjugated to tyrosine (ET 1) and phenylalanine (EP 1). Superoxide dismutase (SOD) activity was exhibited for Cu(II) but not the Fe(III) complexes. The mimetic activities were compared to bovine erythrocyte SOD (3730 U/mg) and exhibited activities of 1119 U/mg for ET 1-Cu(II) and 551 U/mg for EP 1-Cu(II). Thus, small alterations in structure can have significant effects on the enzymatic activity of metallopeptides. These synthetic chelators have dual potential anti-inflammatory activity by chelating deleterious non-protein bound metal ions and concomitantly affording anti-oxidant mimetic activity.

An electrochemical study on bovine erythrocyte superoxide dismutase ? the novel electrochemical behaviors on mercury electrodes

The electrochemical behavior of bovine erythrocyte superoxide dismutase (BESOD) on a hanging or dropping mercury electrode was studied by cyclic voltammetry (CV) and normal pulse polarography (NPP). Two defined peaks in CV or in NPP diagrams were attributed to the peaks of copper(II) and zinc(II), respectively. The electrode processes were irreversible and possessed an adsorptive characteristic. The adsorption of BESOD was estimated by double potential-step chronocoulometry. The average area of each molecule of absorbed BESOD was obtained, which is in good agreement with that determined by X-ray structure analysis. The diffusion coefficients were determined by NPP and double potential-step chronocoulometry, being in agreement with each other. The experimental results confirm that in the absence of a promotor or mediator, mercury electrodes are feasible for the investigation of BESOD.

An electrochemical study on bovine erythrocyte superoxide dismutase – the novel electrochemical behaviors on mercury electrodes

The electrochemical behavior of bovine erythrocyte superoxide dismutase (BESOD) on a hanging or dropping mercury electrode was studied by cyclic voltammetry (CV) and normal pulse polarography (NPP). Two defined peaks in CV or in NPP diagrams were attributed to the peaks of copper(II) and zinc(II), respectively. The electrode processes were irreversible and possessed an adsorptive characteristic. The adsorption of BESOD was estimated by double potential-step chronocoulometry. The average area of each molecule of absorbed BESOD was obtained, which is in good agreement with that determined by X-ray structure analysis. The diffusion coefficients were determined by NPP and double potential-step chronocoulometry, being in agreement with each other. The experimental results confirm that in the absence of a promotor or mediator, mercury electrodes are feasible for the investigation of BESOD.

Protective effect of coadministered superoxide dismutase and catalase against stress-induced gastric mucosal lesions.

1. There are conflicting reports as to the protective effect of coadministered native superoxide dismutase (SOD) and catalase against gastric mucosal lesions in rats with water immersion restraint (WIR) stress. It is unclear how coadministered native SOD and catalase protect against WIR stress-induced gastric mucosal lesions. Therefore, in the present study, we re-examined the protective effect of coadministered native SOD and catalase against gastric mucosal lesions in rats with WIR stress. 2. Gastric mucosal lesions were induced in Wistar rats by 3 h WIR. Rats were injected subcutaneously with a mixture of purified bovine erythrocyte SOD and bovine liver catalase 1 h before the onset of WIR. Ulcer index, serum SOD, catalase and xanthine oxidase (XO), uric acid and gastric mucosal SOD, catalase, XO, myeloperoxidase (MPO; an index of tissue neutrophil infiltration), non-protein sulfhydryl (NP-SH) and thiobarbituric acid-reactive substances (TBARS; an index of lipid peroxidation) were assayed in all rats used. 3. Rats with 3 h WIR showed gastric mucosal lesions. Pre-administration of SOD plus catalase to rats with WIR prevented lesion formation. In the serum of rats with WIR alone, XO activity and uric acid concentration increased, whereas SOD and catalase activities did not change. Pre-administration of SOD plus catalase to rats with WIR did not affect increased serum XO activity and uric acid concentration, but did increase serum SOD and catalase activities. In the gastric mucosa of rats with WIR alone, increases in MPO activity and TBARS concentration and a decrease in NP-SH concentration occurred, whereas XO, SOD and catalase activities did not change. Pre-administration of SOD plus catalase to rats with WIR attenuated the changes in gastric mucosal MPO activity and TBARS and NP-SH concentrations, but did not affect gastric mucosal XO, SOD and catalase activities. Pre-administration of SOD plus catalase (in an inactivated form) to rats with WIR had no effect on gastric mucosal lesion formation and the levels of serum and gastric mucosal parameters studied. 4. These results indicate that coadministered native SOD and catalase protect against gastric mucosal lesions in rats with WIR stress and suggest that this protective effect of coadministered native SOD and catalase could be due to their activity to scavenge XO-derived active oxygen species that are increased in the blood.

Antioxidant activity of nasunin, an anthocyanin in eggplant peels

The free radical scavenging activities and inhibitory effect of lipid peroxidation of a delphinidin derivative in eggplant were investigated. Delphinidin-3-( p-coumaroylrutinoside)-5-glucoside (nasunin), an anthocyanin, was isolated as purple colored crystals from eggplant peels. Using electron spin resonance spectrometry and 5,5-dimethyl-1-pyrroline- N-oxide (DMPO), hydroxyl radicals ( OH) or superoxide anion radicals (O 2 −) generated by the Fenton reaction or the hypoxanthine-xanthine oxidase system were measured as DMPO–OH or DMPO–OOH spin adducts. l-Ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6yl-hydrogen phosphate] potassium salt (EPC-K1) and bovine erythrocyte superoxide dismutase (SOD) were used as standards for OH and O 2 − scavengers, respectively. Nasunin showed potent O 2 − scavenging (143±8 SOD-equivalent U/mg) and OH scavenging (0.65±0.07 EPC-K1-equivalent μmol/mg) activities. Then, by changing the concentration of DMPO to vary the trapping rate of OH, the presence of a competitive reaction between nasunin and OH was studied. The 50% inhibition dose (ID 50) obtained from the inhibition curve did not change, indicating OH scavenging of nasunin is not due to direct scavenging but inhibition of OH generating system by chelating ferrous ion. Nasunin protection against H 2O 2-induced lipid peroxidation in rat brain homogenate was measured at 586 nm using the indicator of malonaldehyde and 4-hydroxyalkenals. Nasunin (<50 μM) protected against lipid peroxidation of brain homogenates. The findings suggest that nasunin is a potent O 2 − scavenger and has protective activity against lipid peroxidation.

Two and Three Dimensional Nuclear Quadrupole Resonance in the Investigation of Structure and Bonding

A variety of two dimensional two-and three-dimensional NQR experiments are reviewed, showing their application to the determination of field gradients for important sites in peptides and proteins, for assigning connected transitions of nuclei with spin ≥ 5/2, and for determining hexadecapolar coupling constants. The quadrupole coupling tensor for 63Cu in the active site of a protein, bovine erythrocyte (Cu, Zn) superoxide dismutase, has been measured and is compared with the results of ab initio calculations.

Elimination of superoxide dismutase interference in fructosamine assay

Objective: Superoxide dismutase (SOD) (EC 1.15.1.1) is reported to decrease the reduction of nitroblue tetrazolium (NBT) in the fructosamine assay. The study was undertaken to find a method to eliminate this interference. Design and Methods: We studied the NBT reduction in the presence and absence of added bovine erythrocyte SOD during fructosamine assay. Formation of reduced NBT decreased with the increasing concentration of SOD. Various inhibitors of SOD were experimented with for effectively eliminating this interference. Results: Cyanide eliminates the interference due to SOD, but is unsuitable because in it’s presence glucose becomes reducing under the conditions of fructosamine assay. SOD inhibitors such as EDTA and Azide did not eliminate the effect of SOD. Guanidine. HCl gives opalescence in the reaction mixture. Addition of 2M HCl to the serum and incubation at 37 °C for 10 min eliminated the effect of added SOD (70 kU/L).The correlation between δA 10–20 min of serum treated with HCl in presence and absence of added SOD is y = 0.9011 x + 0.01055 with r = 0.9789 and S.E. (y) 0.007686. Conclusion: SOD does not interfere in globin bound fructosamine assay as acid-acetone treatment in preparation of heme free globin inhibits SOD. Pretreatment of serum with HCl can satisfactorily eliminate the interference due to SOD in fructosamine assay. The acid treatment could be used to inhibit SOD in various other reactions that are followed with NBT reduction.

Anti-inflammatory effect of the conjugate of superoxide dismutase with the copolymer of divinyl ether and maleic anhydride against rat re-expansion pulmonary edema

Bovine erythrocyte superoxide dismutase (SOD) was conjugated with the copolymer of divinyl ether and maleic anhydride, known as DIVEMA or pyran copolymer. The DM–SOD conjugate was resistant against the proteolytic enzymes in serum, and showed a prolonged half-life in vivo after intravenous injection. DM–SOD was applied for the treatment of rat lung edema caused by the re-expansion after the left bronchus has been clipped for 3 days. The anti-inflammatory effect was evaluated by the inhibition rate of the water content due to the edema. Neither SOD nor DIVEMA reduced the increase in water content in the lung, whereas DM–SOD could effectively protect against the increase in water content such that the water content of the re-expanded lung was the same as that of the control right lung. Using electron microscopic observation the difference between the SOD and DM–SOD treatment in the water swelling of the interalveolar septum was clearly indicated. Observation of the surface of the endothelial wall in the blood vessel of the lung showed more a drastic difference. The leukocyte attachment on the endothelial layer observed following the treatment with SOD was not observed following that with DM–SOD. This observation indicates that DM–SOD had stopped the inflammation process at the first step of leukocyte adhesion, which should be followed by the rolling and expansion of the leukocytes to initiate the normal inflammation process.

Free Radical-Mediated Tissue Injury in Acute Lung Allograft Rejection and the Effect of Superoxide Dismutase

Background. The role of monocytes and neutrophils is crucial during acute allograft rejection. They have the capacity to generate toxic reactive oxygen intermediates in response to specific agonists that may act as tissue destructive molecules. We examined the possibility of reactive oxygen intermediate-mediated tissue injury in acute lung allograft rejection, as well as the effect of superoxide dismutase. Methods. Allogenic (Brown Norway to F344) or syngeneic (F344 to F344) rat left-lung transplantation was performed. Generation of reactive oxygen intermediates in peripheral blood was evaluated by the method of luminol-dependent chemiluminescence. Cell membrane phospholipid peroxidation in the graft was measured as malondialdehyde concentration. The third group of animals having allografts received bovine erythrocyte superoxide dismutase (5,000 U/kg intravenously every 12 hours after transplantation). Results. Relative chemiluminescence response in the allograft recipient to normal F344 was elevated on postoperative day 1 (257%), then decreased slightly on day 3 (156%) and was elevated again on day 7 (560%) as the process of rejection progressed. Allograft tissue malondialdehyde levels (248.37 ± 112.35 nM/whole lung, n = 6; p < 0.05 by Student’s t test) were higher than isograft levels (139.29 ± 35.93 nM/whole lung, n = 6) on day 7. Superoxide dismutase treatment significantly ameliorated the histologic degree of rejection on day 7. Conclusions. These results demonstrate the tissue destructive activity of reactive oxygen intermediates during lung allograft rejection. To scavenge free radicals may be a useful therapeutic modality in the management of acute lung allograft rejection.

High Superoxide Dismutase Activity of a Novel, Intramolecularly Imidazolato-Bridged Asymmetric Dicopper(II) Species. Design, Synthesis, Structure, and Magnetism of Copper(II) Complexes with a Mixed Pyrazole-Imidazole Donor Set.

A new dinucleating ligand, 1,5-bis(1-pyrazolyl)-3-[bis(2-imidazolyl)methyl] azapentane (Hbpzbiap), containing pyrazoles and imidazoles has been designed and synthesized. The synthesis and characterization of the copper complexes with the ligand Hbpzbiap and its dehydronated form are described. This study is aimed at modeling the active site of copper-zinc superoxide dismutase (SOD). Single crystals of the imidazolato-bridged complex [Cu(2)(bpzbiap)Cl(3)] (1) and non-imidazolato-bridged complex [Cu(2)(Hbpzbiap)Cl(4)] (2) were obtained and their structures determined by X-ray diffraction. Both structures show two copper centers in two different coordination environments: a distorted square pyramid and a distorted tetrahedron. The Cu-nitrogen bond lengths range from 1.919(4) to 2.039(3) Å and are as expected. The copper-copper distances from 5.566(1) to 6.104(1) Å being only slightly shorter than that found in bovine erythrocyte SOD. Temperature-dependent magnetic susceptibility study of 1 shows antiferromagnetic behavior with -2J = 96 cm(-)(1). From pH-dependent electron paramagnetic resonance and electronic spectra, [Cu(2)(bpzbiap)Cl(3)] has been demonstrated to be stable over a quite wide pH range including the physiological pH values. A low concentration of this complex (1) catalyzes the dismutation of superoxide at biological pH. Voltammetric studies indicate a quasi-reversible redox behavior in aqueous solution at pH 7. These results clearly indicate that complex 1 is a good model for superoxide dismutase.

Effect of Superoxide Dismutase on Apoptosis in Ischemia-Reperfused Myocardium of Rabbit

Background:Recently involvement of apoptosis, or programmed cell death, has been suggested in myocardial reperfusion injury. Free radicals are one of the inducers of apoptosis, and superoxide dismutase(SOD), a oxygen free radical scavenger, inhibits apoptotic cell death of neurons. Reperfusion of ischemic myocardium results in a burst of oxygen free radical production, however, it has not been defined that oxygen free radicals mediate apoptosis in myocardial reperfusion injury. This study was undertaken to investigate the role of oxygen free radicals by examining the inhibition of apoptosis by SOD. Method:New Zealand white rabbits(n=16) weighing 1.8-2.0kg underwent 30 minutes of left anterior descending coronary artery occlusion followed by reperfusion for 1 or 4 hours. In control group, bovine serum albumin(5mg/kg) was administered continuously via the left atrial appendage starting 10 minutes before reperfusion and ending simultaneously with reperfusion for 1 hour(n=4) or 4 hours(n=4). In SOD group, bovine erythrocyte SOD(15,000u/kg) was administerd starting 10 minutes before reperfusion and ending simultaneously with reperfusion for 1 hour(n=5) or 4 hours(n=3). Ventricles were excised immediately after intervention. Tissues were fixed in 10% buffered formalin and 2.5% glutaraldehyde. Apoptosis was examined by hematoxylin and eosin(H & E) staining, in situ nick end labeling, and transmission electron microscopy. Number of apoptotic cells was evaluated semiquantitatively on H & E stained section. Results:Evidence of apoptosis was detected in every ischemia-reperfused myocardium, and apoptotic cells were found in the non-necrotic myocardium near areas of contraction band necrosis. In control group, the average number of apoptotic cells was 1.7(range 1.5-2.0) for 1 hour reperfused

Crystal Structure of Reduced Bovine Erythrocyte Superoxide Dismutase at 1.9 Å Resolution

Cu, Zn superoxide dismutase was investigated crystallographically in the reduced form. Co-ordinate errors were estimated by comparing two independently refined models, based on two different data sets. This gave a detailed error estimation as opposed to the standard σ Aand Luzzati plots, which estimate only the overall error. The high quality of the final model, obtained after scaling together two data sets, combined with the error estimates allowed a detailed analysis of the protein and solvent structures. An automatic procedure for building and refining solvent structure was tested and found to give reproducible results. Contrary to results obtained from spectroscopic studies, the co-ordination of the metal ions in the catalytic site is preserved in the crystal structure of the reduced enzyme, as compared with the crystal structure of the oxidised form. Analysis of the solvent reveals a well-defined chain of closely packed, hydrogen-bonded water molecules filling the active site groove. This structural feature could serve as a hydrogen bond relay for efficient delivery of protons to the active centre. Analysis of electron density suggests that Glu119 is covalently modified. The modification, if originated in vivo, could have a role in the catalytic mechanism and could affect the overall electrostatic field in the active site. There are significant differences between the active sites of the two crystallographically independent monomers. They are explained in terms of local differences in the crystal environment. f2 f2 Abbreviations used: SOD, Cu,Zn superoxide dismutase; EXAFS, extended X-ray absorption fine structure; EPR, electron paramagnetic resonance.

The calf thymus superoxide dismutase: a protein active on cholesterol metabolism

1. 1. Recent studies on the new aspects of thymus physiology describing the correlation between thymus hormones and pituitary hormone secretion, are illustrated. 2. 2. Subsequently, results of a series of experiments showing the effect of a calf thymus protein on cholesterol synthesis in rat hepatocyte cells are discussed. 3. 3. The last part of this review is focused on the biochemical characteristics of this calf thymus protein that revealed an amino acid sequence that was found to be identical with regions of bovine erythrocyte superoxide dismutase. New perspectives of studies, focused on the isolation of possible superoxide dismutase membrane receptors, are described at the end of this review.

Formate as an NMR probe of anion binding to Cu,Zn and Cu,Co bovine erythrocyte superoxide dismutases.

The binding of formate to bovine Cu,Zn superoxide dismutase has been studied by NMR spectroscopy. The distance between the copper ion and the proton covalently bound to formate has been evaluated from the broadening of the resonance of such proton. The effect on the copper-coordinated water molecule was evaluated from the bulk water relaxation effect by pulsed low-resolution NMR. The broadening of the resonance due to the formate carboxyl in the 13C NMR spectrum gave further indications about the carbon-copper distance thus providing information about the orientation of the formate ion. Changes of isotropically shifted resonances of the Cu,Co enzyme, where cobalt substitutes the native zinc, indicate that rearrangements of imidazoles of the liganding histidines occur upon binding. Transient NOE experiments gave indication of the proximity of the formate proton to resonance H of the NMR spectrum assigned to the imidazole proton of the copper-liganding His 118 of the active site. 2D NMR NOESY experiments made clear that no important rearrangement of the liganding histidines occurred in the presence of a saturating amount of formate. The absence of relevant changes of the intensity of NOE cross-peaks which are sensitive to interatomic distances in the active site revealed that only slight changes have occurred. Molecular graphics representation on the basis of all the information obtained allowed us to locate the formate in the proximity of the active site. The formate binding occurs via hydrogen bonds through the carboxylate ion and the NH groups of the side chains of Arg 141 which is external to the copper coordination sphere and faces the active site of the enzyme.

Crystal structure solution and refinement of the semisynthetic cobalt-substituted bovine erythrocyte superoxide dismutase at 2.0 Å resolution

The semisynthetic Co-substituted bovine erythrocyte superoxide dismutase (SOD) has been crystallized in a new crystalline form and the structure determined at 2.0 Å (1 Å = 0.1 nm) resolution. The crystals belong to space group P2 12 12 1 with cell constants: a = 51.0, b = 147.6, c = 47.5 A ̊ , and contain one dimeric molecule of 32,000 M r per asymmetric unit. The structure has been solved by molecular replacement techniques using the Cu,Zn bovine enzyme as a search model, and refined by molecular dynamics with the crystallographic pseudo-energy term, followed by conventional crystallographic refinement. The R-factor for the 18,964 unique reflections in the resolution range from 10.0 to 2.0 Å is 0.176 for a model comprising 2188 protein atoms and 200 solvent molecules; the root-mean-square deviation from the ideal bond lengths is 0.010 Å, and the average atomic temperature factor is 26.5 Å 2. The dimeric molecule of the enzyme is composed of two identical subunits related by a non-crystallographic 2-fold axis. The subunit has as its structural scaffolding the conventional SOD-flattened antiparallel eight-stranded β-barrel, with three external loops. The co-ordination geometry of the metal center in the active site is fairly well preserved when compared with the native Cu,Zn bovine enzyme. Co 2+ is in tetrahedral co-ordination, while the Cu 2+ ligands show an uneven distortion from the square planar geometry. The least-squares superposition of the metals ligands and the catalytically important Arg141 of the native and Co-substituted enzyme yields a root-mean-square value of 0.401 Å, the largest deviation occurring at the Co 2+ ligand Asp81. An additional copper ligand, compatible with a water molecule, is observed at 2.38 Å from Cu 2+ in the active-site channel, at the supposed binding site of the O 2 − anion substrate. Several ordered water molecules have been observed on the protein surface and in the active-site channel; their structural locations coincide remarkably with those of related water molecules found in the crystal structure of the phylogenetically distant superoxide dismutase from yeast.

Deblocking and subsequent microsequence analysis of N alpha-blocked proteins electroblotted onto PVDF membrane.

A method was developed for direct microsequencing of N alpha-acetylated proteins electroblotted onto polyvinylidene difluoride membranes from polyacrylamide gels. N alpha-Acetylated proteins (greater than 32 pmol), including horse heart cytochrome c, five mutants of yeast cytochrome c, and bovine erythrocyte superoxide dismutase, were separated by SDS-PAGE and electroblotted onto polyvinylidene difluoride membranes. The portions of the membrane carrying the bands were cut out and treated with 0.5% polyvinylpyrrolidone in acetic acid solution at 37 degrees C for 30 min. The protein was digested on the membrane with 5-10 micrograms of trypsin at 37 degrees C for 24 h. During tryptic digestion, the resultant peptides were released from the membrane and the N-terminal peptide was efficiently deblocked with 50 mU of acylamino acid-releasing enzyme at 37 degrees C for 12 h. Picomole levels of the deblocked proteins could be sequenced directly by use of a gas-phase protein sequencer.

Voltammetric behaviour of bovine erythrocyte superoxide dismutase

The activity of several enzymes, including those involved in N, fmation, photosynthesis and respiration, is linked to electron storage and transport processes [l]. Therefore, electrochemical properties, such as the formal redox potential (E”) and the number of electrons stored in the molecule, are aspects of primary importance in the chemistry of these kinds of proteins. Classical potentiometric, spectrophotometric and coulometric methods and more recent techniques such as cyclic voltammetry and differential pulse polarography [2] can be used in the determination of these parameters. It is well known that, in general, redox proteins do not show a reversible electrochemical response at mercury and solid electrodes [3]. In several cases, surface modification [4] by adsorption of a suitable molecule (promoter) enhances the rate of the electron transfer and the reversibility of the electrochemical process, thus allowing the use of voltammetric or polarographic techniques in the study of the redox behaviour of enzymes. Bovine erythrocyte superoxide dismutase (BESOD) is a metallo-enzyme containing one Cu”-Zn” pair in each of the two subunits of the molecule [5,6]. Copper and zinc are connected by an imidazole bridge of a histidine residue.

Novel low‐molecular‐weight superoxide dismutase mimic deferoxamine‐manganese improves survival following hemorrhagic and endotoxic shock

AbstractThe purpose of this study was to demonstrate the in vivo activity of the novel low‐molecular‐weight superoxide dismutase (SOD)‐mimic deferoxamine‐manganese (Def‐Mn) in models of circulatory shock. Two forms of Def‐Mn were examined: the pink‐complex (NPC 14550) and the green complex (NPC 15823). Hemorrhagic shock was induced in rats (40 mmHg, 60 min) followed by autotransfusion of shed blood, and endotoxic shock (LPS, 200 μg/10g BW) was induced in mice. Significant lethality (ca. 20% survival rate at 24 hr) was observed in each model. Following hemorrhagic shock, NPC 14550 (10 mg/kg) increased the 24‐hr survival rate to 48% (P=0.03), while NPC 15823 (10 mg/kg) did not significantly alter survival rate (30%, P &gt; 0.05). Following endotoxin challenge, both NPC 14550 and NPC 15823 significantly improved the 24‐hr survival rate to 68% (P≤0.001) and 55% (P=0.002), respectively. Bovine erythrocyte SOD and polyethylene glycol‐SOD (Peg‐SOD) also afforded significant protection in these models and, as anticipated, SOD afforded transient protection, while Peg‐SOD provided significant protection for 24 hr and longer. Deferoxamine mesylate provided only transient protection. It is concluded that the SOD‐mimic Def‐Mn has beneficial effects following circulatory shock and, furthermore, these data provide additional evidence that the superoxide radical does play a role in these disorders.